Title:
Origin of the Oort Cloud
Alessandro Morbidelli
Observatory of Nice
France
Abstract:
Comets are the most primitive objects in the Solar System. Many
scientists think that they have kept a record of the physical and
chemical processes that occurred during the early stages of the
evolution of our Sun and Solar System. The abundance of volatile
material in comets makes them particularly important and
extraordinary objects. This characteristic demonstrates that comets
were formed at large distances from the Sun and have been preserved
at low temperatures since their formation. Cometary material
therefore represents the closest we can get to the conditions that
occurred when the Sun and our Solar System were born.
The old view of a vast region of empty space extending from Pluto (40
AU) to the Oort Cloud (10000 AU) has been conclusively replaced by a
picture of a volume richly populated by unexplored new worlds.
Ground-based surveys in the past few years have discovered over 1000
icy bodies beyond Neptune, members of a population called the `Kuiper
Belt'. Kuiper Belt bodies are related to a wide range of outer Solar
system members, such as the short-period comets, the Neptunian
satellite Triton, and the Pluto-Charon system -- indeed, Pluto is now
recognized as the largest known member of the Kuiper Belt. The
connection between Kuiper Belt objects and so many different Solar
system bodies hints at a common origin in the outer Solar system -- a
remarkable hypothesis considering the diverse characteristics of
these bodies. The Kuiper Belt is also our closest link to the
circumstellar disks found around other main sequence stars, and an
understanding of the physical processes operative in the Belt (both
now and in its ear